Pest profile

European Elm Scale

Gossyparia spuria · Hemiptera: Eriococcidae[2]

European elm scale is a soft scale ringed with white wax that feeds on elm twigs, branches and leaves, dripping honeydew and killing twigs in heavy infestations.[1]

Reddish-brown European elm scales ringed with white wax on an elm branch
Reddish-brown European elm scales ringed with white wax on an elm branch. (c) Daniel S., some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • Mature females are reddish brown to purplish and surrounded by a conspicuous fringe of white wax; they sometimes look like mealybugs.[1]
  • Crawlers are yellowish to dark brown and appear in late spring and summer.[1]
  • Sticky honeydew and black sooty mold on leaves are common signs.[1]

Look-alikes

Look-alikeHow to tell them apart
MealybugsEuropean elm scales sometimes resemble mealybugs; look for reddish-brown scales ringed with white wax on elm twigs.[1]

Where it lives

The PNW Insect Management Handbook covers it on elms in the Pacific Northwest.[1]

US map: public records from 24 states since 1990 (GBIF).

Biology and life cycle

It overwinters as immature crawlers in bark crevices of small branches and in branch axils.[1]

Females lay eggs in spring; crawlers are active by June and move to leaf undersides for the summer, often dying when the leaves drop.[1]

There's one generation a year.[1]

Damage and signs

  • Infested trees may show yellowing leaves and early leaf drop, then dying twigs and branches; severe infestations can cause extensive damage.[1]
  • Honeydew attracts ants and grows black sooty mold.[1]

Health risk

It feeds on plants; the PNW Insect Management Handbook mentions no risk to people.[1]

Control

Prevention

Chinese elm and other Asiatic elms aren't infested, and Siberian elm resists it, though it's a poor shade tree.[1]

Keep trees healthy and avoid excess nitrogen fertilizer, which favors scale buildup.[1]

Traps and physical control

Prune out isolated infestations, and wrap tape near adult scales, sticky side out, to catch crawlers.[1]

Biological control

Lady beetles, green lacewings and parasitic wasps help control it; avoid broad-spectrum insecticides that kill them.[1]

Pesticides

Dormant-season sprays need enough water to cover the whole tree; growing-season sprays target crawlers, usually late spring to early summer.[1]

Common questions

What are the reddish scales with white fringes on my elm?
Probably European elm scale, a soft scale ringed with white wax.[1]
Which elms resist European elm scale?
Chinese elm and other Asiatic elms aren't infested, and Siberian elm is resistant.[1]

Sources

  1. Pacific Northwest Pest Management Handbooks (OSU, WSU, University of Idaho), “Elm (Ulmus): European elm scale (Insect Management Handbook).” pnwhandbooks.org/insect/hort/landscape/hosts-pests-landscape-plants/elm-ulmus-european-elm-scale (accessed 2026-10-06)
  2. iNaturalist, “Gossyparia spuria taxon page (order and family).” www.inaturalist.org/taxa/1514433 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.